The present invention relates to servo systems and particularly to a passive tracking servo system for mirror elements in a steerable Fresnel solar energy collector.
Large-scale solar radiation collectors, based on the principle of the steerable Fresnel mirror, have been previously proposed. Such collectors comprise a large array of mirrors, each of about one square meter, arranged in concentric circles on a flat ground. Solar radiation is focused, as shown in FIG. 1, onto a solar target device, such as a steam boiler, for example, for converting thermal energy to electrical energy through a conventional thermodynamic cycle. However, a major problem is in controlling the attitude of each mirror element such that the sun is continuously tracked and focused with maximum precision onto the conversion device (i.e., solar target).
Due to restrictions on fossil fuel power plants, there is a need for solar energy power generating facilities. At various land facilities which have large areas of flat ground, it is possible to install the type of solar collector/focuser needed for generating relatively large amounts of power. Rain water can be used to supply the hydrostatic head for providing rotational energy for each Fresnel reflector. Where rain water is used, a sufficiently large area is needed for collection of rain water in sufficient quantity to renew, daily, the hydrostatic head requirements.